Moisture absorbing formed article

ABSTRACT

An object of the present invention is to provide a material which can absorb moisture with ease and certainly, which exists in an equipment such as an electronic device. The invention relates to a moisture absorbing formed body comprising a hygroscopic agent and a resinous component.

TECHNICAL FIELD

[0001] The present invention relates to a moisture absorbing formedbody.

BACKGROUND ART

[0002] Electronic devices such as batteries, capacitors (condensers),display units and so forth are steadily heading for further down sizingand weight reduction. These electronic parts are sealed, withoutexception, with a rubber sealant or a resin adhesive such as UV-curableresin in the stage of sealing the outer housing. However, when such asealing technique is used, the moisture penetrating through the sealantduring storage or use detracts from the performance of the electronicparts. Thus, the moisture finding its way into an electronic device maycause a degradation or corrosion of electronic parts within the device.For example, in a battery or capacitor using an organic electrolyte,contamination of the electrolyte with water causes not only changes inelectrical conductivity, electrolysis of the invading water, etc. butalso a voltage depression across the terminals and distortion andleakage of the housing due to evolution of gases. Thus, owing to themoisture infiltrating into electronic devices, the functional stabilityand reliability of the devices can hardly be maintained.

[0003] To overcome this disadvantage, the so-called hermetic sealing ormetal welding might be considered. However, with such techniques,swelling of the package housing or distortion of the housing due tointernal pressure reduction would occur to induce chemical changes inthe internal functional component materials.

[0004] On the other hand, in the stage of assembling such as electronicdevice, it is practically impossible to control humidity at 0 throughoutthe stage. Therefore, for example, in the aging stage after completionof an electronic device, it is indispensable to absorb the moisturewhich has infiltrated into the electronic device during its assembling.However, as mentioned above, there has not been established a technologyby which the moisture infiltrating into an electronic device can beabsorbed infallibly and easily.

DISCLOSURE OF INVENTION

[0005] A primary object of the present invention, therefore, is toovercome the above-mentioned drawbacks of the prior art and provide anformed body capable of absorbing the moisture infiltrating into theinterior of a device, such as an electronic device, with ease andwithout fail.

[0006] In view of the above disadvantage of the prior art, the inventorof the present invention did intensive investigations and found that aherein-defined moisture absorbing shaped article is capable ofaccomplishing the above object. The inventor has accordingly perfectedthis present invention.

[0007] The present invention, therefore, relates to the followingmoisture absorbing formed bodies.

[0008] 1. A moisture absorbing formed body comprising a hygroscopicagent and a resinous component.

[0009] 2. A moisture absorbing formed body according to Paragraph 1wherein the hygroscopic agent comprises at least one member selectedfrom the group consisting of the oxides and sulfates of alkaline earthmetals.

[0010] 3. A moisture absorbing formed body according to Paragraph 1wherein the hygroscopic agent is at least one member selected from thegroup consisting of CaO, BaO and SrO.

[0011] 4. A moisture absorbing formed body according to Paragraph 1wherein the hygroscopic agent is a powder having a specific surface areaof not less than 10 m²/g.

[0012] 5. A moisture absorbing formed body according to Paragraph 1wherein the hygroscopic agent is a powder having a specific surface areaof not less than 40 m²/g.

[0013] 6. A moisture absorbing formed body according to Paragraph 1wherein the hygroscopic agent accounts for 30-95 weight %of the moistureabsorbing formed body.

[0014] 7. A moisture absorbing formed body according to Paragraph 1wherein the resinous component is at least one member selected from thegroup consisting of fluorine-containing resin, polyolefin resin,polyacrylic resin, polyacrylonitrile resin, polyamide resin, polyesterresin and epoxy resin.

[0015] 8. A moisture absorbing formed body according to Paragraph 1further comprising a gas absorbent.

[0016] 9. A moisture absorbing formed body according to Paragraph 8wherein the gas absorbent comprises an inorganic porous substance.

[0017] 10. A moisture absorbing formed body according to Paragraph 1,the surface of which is covered wholly or in part with a resinouscovering layer.

[0018] 11. A moisture absorbing formed body according to Paragraph 1,wherein the resinous component has been fibrillated.

[0019] 12. A moisture absorbing formed body according to Paragraph 1,wherein the hygroscopic agent is a powder composed of at least onemember selected from the group consisting of CaO, BaO and SrO which hasa specific surface area of not less than 10 m²/g and the resinouscomponent is a fluorine-containing resin (fluororesin).

[0020] 13. A moisture absorbing formed body according to Paragraph 12wherein the fluorine-containing resin has been fibrillated.

[0021] 14. A moisture absorbing formed body according to Paragraph 1 forelectronic device use.

[0022] The moisture absorbing formed body of the present inventioncomprises a hygroscopic agent and a resinous component. The morphologyor geometry of the moisture absorbing formed body is not restricted butcan be judiciously selected according to the mode of use, purpose ofuse, and site of use of the end product, among other variables, thusincluding sheets, pellets, plates, films, grains (granules), and soforth.

[0023] The hygroscopic agent need only be a substance having at leastthe function of absorbing moisture but is preferably a compound whichadsorbs moisture and retains its solid state even upon adsorption ofmoisture. Among examples of such compound are various metal oxides andsalts of metals with inorganic or organic acids but it is particularlypreferable to use at least one member selected from the group consistingof the oxides of alkaline earth metals and sulfates.

[0024] The oxides of alkaline earth metals include, for example, calciumoxide (CaO), barium oxide (BaO), magnesium oxide (MgO), and strontiumoxide (SrO), or the like.

[0025] As the sulfates, there can be mentioned lithium sulfate (Li₂SO₄),sodium sulfate (Na₂SO₄), calcium sulfate (CaSO₄), magnesium sulfate(MgSO₄), cobalt sulfate (COSO₄), gallium sulfate (Ga₂(SO₄)₃), titaniumsulfate (Ti(SO₄)₂), and nickel sulfate (NiSO₄), among others. Aside fromthe above oxides and sulfates, organic compounds having hygroscopicproperties can also be used as the hygroscopic agent in accordance withthe present invention.

[0026] As the hygroscopic agent for use in the present invention, analkaline earth metal oxide is preferred. Particularly preferred is atleast one member selected from the group consisting of CaO, BaO and SrO.The most preferred is CaO.

[0027] The hygroscopic agent for use in the present invention isformulated preferably in a powdery form. In this case, the specificsurface area (BET specific surface area) of the powder should begenerally not less than 10 m²/g, preferably not less than 30 m²/g,particularly not less than 40 m²/g. As the hygroscopic agent in powderyform, the CaO (powder) obtainable by heating calcium hydroxide at atemperature not over 900° C. (preferably not over 700° C., mostpreferably not over 500° C. (particularly 490-500° C.)), can be usedwith advantage. In the practice of the present invention, a CaO powderhaving a BET specific surface area of not less than 10 m²/g, preferablynot less than 30 m²/g, particularly not less than 40 m²/g, can be usedmost advantageously.

[0028] On the other hand, the resinous component is not particularlyrestricted provided that the water-removing action of the hygroscopicagent is not interfered with, and a gas-permeable polymer (that is tosay a polymer or resin having low gas barrier properties) can be usedwith advantage. For example, there can be mentioned fluorine-containingresin, polyolefin resin, polyacrylic resin, polyacrylonitrile resin,polyamide resin, polyester resin, epoxy resin, and polycarbonate resin.The degree of gas permeability may be judiciously selected according tothe use and desired characteristics of the end product.

[0029] Among these polymers, fluorine-containing resin and polyolefinresin are preferred. As specific examples of the fluorine-containingresin, polytetrafluoroethylene, polychlorotrifluoroethylene,polyvinylidene fluoride, ethylene-tetrafluoroethylene copolymer, etc.can be mentioned. The polyolefin resin includes polyethylene,polypropylene, polybutadiene, polyisoprene, etc. and the correspondingcopolymers. Among these resinous components, the fluororesin isparticularly preferred for purposes of the present invention.

[0030] In the present invention, the formulating levels of saidhygroscopic agent and resinous component may be judiciously selectedaccording to the species of respective materials, among other variables,but the usual proportions based on 100 weight % of the hygroscopic agentand resinous component taken together are about 30-95 weight % of thehygroscopic agent and about 70-5 weight % of the resinous component. Thepreferred formulating levels are about 50-85 weight % of the hygroscopicagent and about 50-15 weight % of the resinous component, and the mostpreferred levels are about 55-85 weight % of the hygroscopic agent andabout 45-15 weight % of the resinous component.

[0031] In the practice of the present invention, within the range notadversely affecting the effect of the invention, other components mayalso be incorporated where necessary. For example, a gas-absorbingmaterial (gas adsorbent) may be added. The gas adsorbent includes, forexample, inorganic porous substances such as silica, alumina, andsynthetic zeolite or the like. The formulating level of the gasadsorbent is not restricted but may generally be about 3-15 parts byweight based on 100 parts by weight of the hygroscopic agent andresinous component taken together.

[0032] Furthermore, where necessary, the moisture absorbing formed bodyof the present invention may be provided with a resinous covering layercontaining a resin material, either all over its surface or in part ofits surface. By means of this layer, the moisture absorbing performanceof the formed body can be better controlled. The resin material of saidresinous covering layer need only be a resin having high gaspermeability and, as such, may for example be any of the materialsmentioned for the resin component of the moisture absorbing formed body.The preferred is said polyolefin resin.

[0033] In the above resinous component, a powder composed of inorganicmaterial or metal may optionally be dispersed, if necessary. By doingso, the durability of the formed body withstanding a sharp change intemperature or humidity can be further enhanced. Particularly, a powder(flaky particles) showing the leafing phenomenon, such as mica, aluminumpowder or the like, is preferred. The formulating amount of said powderis not particularly restricted but may usually be about 30-50 weight %of the resinous covering layer.

[0034] The thickness of the resin covering layer can be judiciouslyselected according to the desired moisture-absorbing capacity and thespecies of resin constituting the resinous covering layer, among othervariables, but may be generally about 0.5-20 μm, preferably 0.5-10 μm.Therefore, the particle diameter of said powder should generally besmaller than the thickness of the resinous covering layer.

[0035] The moisture absorbing formed body of the present invention canbe obtained by blending the respective component materials evenly andforming the blend into a desired shape. In this operation, thehygroscopic agent and said gas adsorbent are preferably dehydrated wellbefore formulation. Moreover, in the blending of the resinous component,the material may be heated into a molten state, where necessary. Theforming or shaping process is carried out using the known techniques.Thus, not only press forming (inclusive of hot pressing), extrusion etc.but also the granulation technique using a rotary granulator, twin-screwgranulator, or the like may be employed.

[0036] When the objective moisture absorbing formed body is a sheet, asheet as formed may be subjected to orientation treatment and used assaid moisture absorbing sheet. The orientation can be effected by theknown technology and may for example be uniaxial or biaxial orientation.

[0037] When the resinous covering layer is provided, the method offorming the layer is not restricted but may for example be the knownlamination method. For example, when the moisture absorbing formed bodyis a sheet, a sheet or film for resin covering layer use, prepared inadvance, can be laminated onto at least one of the face side and reverseside of the moisture absorbing sheet.

[0038] For example, a resinous covering layer (2) may be formed on thereverse side of a moisture absorbing sheet (1) as shown in FIG. 1. Asshown in FIG. 2, a resin covering layers (2)(2) may be formed on each ofthe face and reverse sides of a moisture absorbing sheet (1).

[0039] The thickness of the sheet, when the moisture absorbing formedbody is in sheet form, can be judiciously selected according to theobject of use of the end product, among other factors. For example, whenthe moisture absorbing formed body is to be applied to an electronicdevice such as a capacitor, the thickness may for example be generallyabout 50-400 μm, preferably about 100-200 μm. The sheet thicknessmentioned above is the thickness inclusive of the resinous coveringlayer if present.

[0040] In the moisture absorbing formed body of the present invention,it is preferable that the resinous component should have beenfibrillated. By this fibrillation, a further improved moisture absorbingperformance can be obtained. The fibrillation may be performedsimultaneously with the molding of the moisture absorbing formed body orby post-forming processing. For example, the fibrillation of the resincan be effected by dry-blending the resinous component and hygroscopicagent and rolling the resultant blend. As an alternative, thefibrillation may be effected by subjecting the formed body of theinvention as formed to said orientation treatment. To be more specific,a fibrillated moisture absorbing formed body can be manufactured bydry-blending a powdery hygroscopic agent comprising at least one memberselected from the group consisting of CaO, BaO and SrO with a powderyfluororesin (e.g. polytetrafluoroethylene) and rolling the resultingblend. The rolling and orientation may respectively be carried out usingthe known equipment. The degree of fibrillation can be properlycontrolled according to the use and desired characteristics of the endproduct. The powdery hygroscopic agent is preferably a powder having theabove-defined specific surface area. The fluororesin is not restrictedbut includes the known or commercial powdery (granular) fluororesins assuch.

[0041] The moisture absorbing formed body of the present invention maybe simply located in a position requiring absorption of moisture by theper se known method. For example, for the purpose of dehumidifying theatmosphere within the housing of an electronic device, the moistureabsorbing formed body may be immobilized on part or the whole of theinside surface of the housing. Referring to a capacitor or batteryutilizing an organic electrolyte, the moisture absorbing formed body maybe caused to exist within the organic electrolyte for adsorbing waterfrom the organic electrolyte.

[0042] The method for said immobilization is not particularly restrictedinsofar as the formed body can be securely fixed in position. Forexample, there can be mentioned the method which comprises securing themoisture absorbing formed body to the housing by means of the knownself-adhesive tape or adhesive (preferably a solventless adhesive), themethod which comprises securing the moisture absorbing formed body tothe housing by thermal fusion, and the method which comprises fixing themoisture absorbing formed body to the housing securely with fastenermeans such as small screws, among others.

[0043] Taking a moisture absorbing formed body in the form of a sheethaving a resinous covering layer on each of the face and reverse sidesas an example, when an adhesive layer (3) with release paper (4) isformed on the sheet as shown in FIG. 3, the sheet can be affixed inposition, on the strength of its adhesive layer, after peeling off therelease paper. Moreover, as shown in FIG. 4, the moisture absorbingsheet can be secured to the housing with the aid of a solventlessadhesive (5) based on ethylene-vinyl alcohol copolymer (EVOH) or thelike. As the solventless adhesive, a commercial product can be utilized.

[0044] In accordance with the present invention wherein a moistureabsorbing formed body is used, the moisture infiltrating into anelectronic device or the like can be removed easily and with certainty.

[0045] As a consequence, the placement of desiccating means can bemechanized as well. Thus, chances for moisture finding its way into theinternal atmosphere are reduced and even establishment of an atmospherehaving a high initial level of dryness is feasible. Thus, it is not onlypossible to manufacture devices in highly dry state but also possible toremove moisture with certainty after manufacture, so that devices ofhigher stability and reliability can be provided on a commercial scale.

[0046] Unlike the case in which, as drying means, the conventionaldesiccant (powder) is used directly, the trouble of the powder gettingloose and scattered within the housing can also be avoided. Furthermore,whereas the use of a powder as such makes it imperative to provide aspace for its placement, this is not required in the the presentinvention so that the invention contributes to the down sizing andweight reduction of devices as well.

[0047] The moisture absorbing formed body having these features isexpected to find application in a variety of uses including electroniccomponents, machine parts, automobiles, communications equipment,architectural members, medical materials and precision machinery.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048]FIG. 1 is a view showing an example of the moisture absorbingformed body according to the invention.

[0049]FIG. 2 is a view showing another example of the moisture absorbingformed body according to the invention.

[0050]FIG. 3 is a view showing a still another example of the moistureabsorbing formed body according to the invention.

[0051]FIG. 4 is a view showing another yet example of the moistureabsorbing formed body according to the invention.

[0052]FIG. 5 is a diagrammatic representation of the time course ofweight as determined in Test Example 1.

[0053]FIG. 6 is a diagrammatic representation of the time course ofweight as determined in Test Example 2.

[0054]FIG. 7 is a diagrammatic representation of the time course ofweight as determined in Test Example 3.

[0055]FIG. 8 is a diagrammatic representation of the time course ofweight as determined in Test Example 4.

[0056]FIG. 9 is a diagrammatic representation of the time course ofweight as determined in Test Example 5.

[0057]FIG. 10 is a diagrammatic representation of the time course ofweight as determined in Test Example 6.

BEST MODE FOR CARRYING OUT THE INVENTION

[0058] The following examples are intended to point out the features andadvantages of the the present invention in further detail. It should,however, be understood that the invention is by no means restricted tothese examples.

EXAMPLE 1

[0059] A moisture absorbing formed body in sheet form was prepared.

[0060] The hygroscopic agent CaO powder (purity 99.9%) was sufficientlydehydrated by heating at 900° C. for 1 hour, then cooled in a fallingrate drying atmosphere of 180-200° C., and cooled ultimately to roomtemperature. After 60 weight % of the resulting CaO powder (BET specificsurface area ca 3 m²/g) and 40 weight % of the resinous componentpolyethylene (molecular weight: ca 10×10⁴) were dry-blended, the blendwas melt-kneaded under heating at about 230° C. This kneaded mass wasextruded in sheet form from a T-die to give a moisture absorbing formedbody in the form of a 300 μm-thick sheet.

EXAMPLE 2

[0061] On each of the face and reverse sides of a moisture absorbingsheet of the same formulation as used in Example 1, a resin coveringlayer of low-density polyethylene was laminated by concurrent extrusion(in a thickness of ca 3 μm for each side) to provide a sheet having atotal thickness of 300 μm.

EXAMPLE 3

[0062] On each of the face and reverse sides of a moisture absorbingsheet of the same formulation as used in Example 1, a resin coveringlayer of low-density polyethylene was laminated by concurrent extrusion(in a thickness of ca 12 μm for each side) to provide a sheet having atotal thickness of 300 μm.

[0063] Test Example 1

[0064] With the sheets obtained in Examples 1-3, the change in weightdue to absorption of moisture was monitored in a time series. Thus, eachsample strip (25 mm×14 mm×300μm thickness) was set in an atmospherecontrolled at a temperature of 50° C. and a relative humidity of 80% RHand the rate of weight gain (%) was determined at timed intervals. Therate of weight gain (%) was calculated by means of the followingequation.

[0065] Rate of weight gain (%)=(weight gain of sample strip/weight ofmoisture absorbing formed body before test)×100 The results are shown inTable 1 and FIG. 5. TABLE 1 Time (min) 0 5 10 15 30 60 Example 1 (%)0.00 0.60 1.00 1.40 2.62 5.02 Example 2 (%) 0.00 0.50 0.80 1.20 2.184.37 Example 3 (%) 0.00 0.30 0.60 0.80 1.63 3.19

[0066] In FIG. 5, for comparison's sake, the weight changes determinedwith two kinds of moisture absorbing powders each used alone are alsoshown. In FIG. 5, the closed circle () represents a calcium oxidepowder (purity 99.9%) alone, the open circle (◯) represents a calciumoxide powder (purity 98.0%) alone, the closed triangle (▾) representsExample 1, the open triangle (Δ) represents Example 2, and the blacksquare (▪) represents Example 3.

[0067] The data of FIG. 5 clearly indicate that appropriatemoisture-absorbing effects can be obtained with the moisture absorbingformed bodies of the present invention. It is, therefore, clear that byplacing the moisture absorbing formed body of the invention in anelectronic device or the like, not only the initial moisture within thedevice but also the moisture infiltrating into the device through asealant can be certainly removed.

EXAMPLE 4

[0068] As the hygroscopic agent, SrO powder (particle size 10 μm pass),60 weight %, and as the resinous component, a fluororesin(polytetrafluoroethylene (PTFE)), 40 weight %, were respectively used.These were thoroughly blended in powdery state. Using a calender roll,the resulting blend was rolled into a 300 μm-thick sheet. In this sheet,the PTFE resin had been fibrillated to give an SrO-containing porousstructure.

EXAMPLE 5

[0069] Except that, as the hygroscopic agent, SrO powder (particle size10 μm pass), 60 weight %, and, as the resinous component, polyethylene,40 weight %, were respectively used, the procedure of Example 1 wasotherwise repeated to manufacture a moisture absorbing formed body inthe form of a 300 μm-thick sheet.

EXAMPLE 6

[0070] Except that, as the hygroscopic agent, the same CaO powder asused in Example 1 was used, the procedure of Example 4 was otherwiserepeated to manufacture a fibrillated resin sheet having a thickness of300 μm.

[0071] Test Example 2

[0072] With the sheets obtained in Examples 4 and 5, the change inweight due to moisture absorption was investigated in a time series.Each sample strip (25 mm×14 mm×300 μm thickness) was set in anatmosphere controlled at a temperature of 20° C. and a relative humidityof 65% RH and the rate of weight gain (%) was determined at timedintervals. The rate of weight gain was calculated by the same procedureas used in Test Example 1. The results are shown in Table 2 and FIG. 6.TABLE 2 Time (min) 0 5 10 15 30 60 Example 4 (%) 0.0 3.3 5.7 7.6 13.117.1 Example 5 (%) 0.00 0.03 0.06 0.09 0.45 1.16

EXAMPLE 7

[0073] As the hygroscopic agent, a CaO powder having a BET specificsurface area of 48 m²/g (particle size 10 μm pass), 60 weight %, and, asthe resinous component, polyethylene (molecular weight: ca 10×10⁴), 40weight %, were respectively used. These were dry-blended and the blendwas melt-kneaded under heating at about 230° C. The kneaded mass wasextruded in sheet form from a T-die to manufacture a moisture absorbingformed body in the form of a 300 μm-thick sheet. As said CaO powder,calcium hydroxide baked in a nitrogen gas at 500° C. and adjusted to theabove-mentioned specific surface area was used.

EXAMPLE 8

[0074] As the hygroscopic agent, the same CaO powder as used in Example7, 60 weight %, and, as the resinous component, a fluororesin(polytetrafluoroethylene (PTFE) powder, 40 weight %, were respectivelyused. These were thoroughly blended in powdery state. Using a calenderroll, the resulting blend was rolled into a 300 μm-thick sheet. In thissheet, the PTFE resin had been fibrillated to give a CaO-containingporous structure.

Test Example 3

[0075] With the sheets obtained in Examples 7 and 8, the change inweight due to moisture absorption was monitored in a time series. Eachsample strip (25 mm×14 mm×300 μm thickness) was set in an atmospherecontrolled at a temperature of 20° C. and a relative humidity of 65% RHand the rate of weight gain (%) was determined at timed intervals. Therate of weight gain was calculated by the same procedure as used in TestExample 1. The results are shown in Table 3 and FIG. 7. The test resultsobtained with the hygroscopic agent (high-specific-area CaO) alone arealso shown. TABLE 3 Time (min) 0 5 10 15 30 60 Example 7 (%) 0.0 0.2 0.40.7 1.4 2.6 Example 8 (%) 0.0 5.1 9.5 12.9 19.8 29.2 High-specific-area0.0 8.7 12.4 15.5 21.4 29.2 CaO (%)

Test Example 4

[0076] With the sheets obtained in Examples 1 and 6, the same test asdescribed in Test Example 3 was performed. The results are shown inTable 4 and FIG. 8. The test data with the hygroscopic agent(low-specific-area CaO) alone are also shown. TABLE 4 Time (min) 0 5 1015 30 60 Example 1 (%) 0.00 0.00 0.00 0.05 0.07 0.07 Example 6 (%) 0.000.02 0.03 0.08 0.17 0.25 Low-specific-area CaO (%) 0.00 0.02 0.04 0.060.16 0.23

EXAMPLE 9

[0077] The hygroscopic agent BaO powder was sufficiently dehydrated byheating at 900° C. for 1 hour, then cooled in a falling rate dryingatmosphere of 180-200° C., and ultimately cooled to room temperature.This BaO, 60 weight %, and the resinous component polyethylene(molecular weight: ca 10×10⁴), 40 weight %, were dry-blended and theblend was melt-kneaded under heating at about 230° C. The kneaded masswas then extruded in sheet form from a T-die to manufacture a moistureabsorbing formed body in the form of a 300 μm-thick sheet.

EXAMPLE 10

[0078] As the hydroscopic agent, the same BaO as used in Example 9, 60weight %, and, as the resinous component, a fluororesin(polytetrafluoroethylene (PTFE)), 40 weight %, were thoroughly blendedin powdery state. Using a calender roll, the resulting blend was rolledinto a 300 μm-thick film. In this sheet, the PTFE resin had beenfibrillated to give a BaO-containing porous structure.

Test Example 5

[0079] With the sheets obtained in Examples 9 and 10, the same test asdescribed in Test Example 3 was performed. The results are shown inTable 5 and FIG. 9. The test results with the hygroscopic agent aloneare also shown. TABLE 5 Time (min) 0 5 10 15 30 60 Example 9 (%) 0.0 0.30.5 0.6 1.7 2.0 Example 10 (%) 0.0 4.9 8.2 11.4 18.2 26.1 BaO powder (%)0.0 6.8 10.6 12.8 18.5 27.3

Test Example 6

[0080] With the sheets obtained in Examples 4, 6, 8 and 10, the sametest as described in Test Example 3 was performed. The results are shownin Table 6 and FIG. 10. TABLE 6 Time (min) 0 5 10 15 30 60 Example 4 (%)0.0 3.3 5.7 7.6 13.1 17.1 Example 6 (%) 0.00 0.02 0.03 0.08 0.17 0.25Example 8 (%) 0.0 5.1 9.5 12.9 19.8 29.2 Example 10 (%) 0.0 4.9 8.2 11.418.2 26.1

[0081] The above results indicate that the moisture absorbing formedbodies according to the present invention are invariably capable ofshowing excellent moisture-absorbing properties. In particular, theformed body of Example 8 as molded using a CaO powder having a high BETspecific surface area of 48 m²/g showed the highest moisture absorbingcapacity. This formed body is considered to be superior to any otherformed body if only from the point of view that CaO is a highly safesubstance.

1. A moisture absorbing formed body comprising a hygroscopic agent and aresinous component.
 2. A moisture absorbing formed body according toclaim 1 wherein the hygroscopic agent comprises at least one memberselected from the group consisting of the oxides of alkaline earthmetals and sulfates.
 3. A moisture absorbing formed body according toclaim 1 wherein the hygroscopic agent is at least one member selectedfrom the group consisting of CaO, BaO and SrO.
 4. A moisture absorbingformed body according to claim 1 wherein the hygroscopic agent is apowder having a specific surface area of not less than 10 m²/g.
 5. Amoisture absorbing formed body according to claim 1 wherein thehygroscopic agent is a powder having a specific surface area of not lessthan 40 m²/g.
 6. A moisture absorbing formed body according to claim 1wherein the hygroscopic agent accounts for 30-95 weight % of themoisture absorbing formed body.
 7. A moisture absorbing formed bodyaccording to claim 1 wherein the resinous component is at least onemember selected from the group consisting of fluorine-containing resin,polyolefin resin, polyacrylic resin, polyacrylonitrile resin, polyamideresin, polyester resin and epoxy resin.
 8. A moisture absorbing formedbody according to claim 1 further comprising a gas absorbent.
 9. Amoisture absorbing formed body according to claim 8 wherein the gasabsorbent comprises an inorganic porous substance.
 10. A moistureabsorbing formed body according to claim 1, the surface of which iscovered wholly or in part with a resinous covering layer.
 11. A moistureabsorbing formed body according to claim 1, wherein the resinouscomponent has been fibrillated.
 12. A moisture absorbing formed bodyaccording to claim 1, wherein the hygroscopic agent is a powder composedof at least one member selected from the group consisting of CaO, BaOand SrO which has a specific surface area of not less than 10 m²/g andthe resinous component is a fluorine-containing resin.
 13. A moistureabsorbing formed body according to claim 12 wherein thefluorine-containing resin has been fibrillated.
 14. A moisture absorbingformed body according to claim 1 for electronic device use.